Power Unit

Fig 1: Climate Control Module Terminal

Courtesy of VOLVO CARS OF NORTH AMERICA.

Climate control module terminal #A26 controls the speed of the blower fan via power unit terminal #3 using a pulse width modulation (PWM) signal which changes according to the setting for the fan selector.

Power unit terminals #4 and #2 then control the negative side of the blower fan motor depending on the pulsed signal from the climate control module.

Fig 2: Relay Coil Resistance/Power Unit Terminals

Courtesy of VOLVO CARS OF NORTH AMERICA.